Field of the Invention
The invention relates to a gas turbine including a first stage having a first guide blade, a first moving blade and a cooling configuration for cooling the first guide blade with air through a first cooling-air feed at the guide blade to be cooled, the cooling-air feed having a first cooling-air supply at a first pressure.
In order to achieve a high efficiency in a gas turbine, it is attempted, on one hand, to achieve gas inlet temperatures which are as high as possible and, on the other hand, to keep the quantity of cooling air required for cooling guide blades and moving blades of a stage as small as possible due to an efficiency loss caused thereby. Guide and moving blades are each disposed in a corresponding blade ring.
The turbine guide blades are supplied with cooling air in stages. The cooling air originates from various bleeds from a compressor of the gas turbine. That is described, for example, in a company brochure entitled "Die 3A-Gasturbinen-Familie von Siemens" [The 3A Gas Turbine Family of Siemens], Siemens Aktiengesellschaft, order No. A96001-U10-A281, February 1995. Therefore, in order to cool the stage and in particular the turbine guide blade, a certain pressure gradient is required and that pressure gradient determines the requisite pressure of the respective bleed.